An IR frequency comb spectrometer could help clinicians detect diabetes, infections and cancers by analyzing the air patients exhale. The system uses a commercial frequency comb, variable-length Fabry-Perot filter cavity, virtually imaged phased array, diffraction grating and near-infrared camera. The cavity length is tuned to gather different spectra and measure the molecular content of gas samples. "Those molecules are by-products of metabolic processes in the body and their levels change when things go wrong," said University of Adelaide research fellow James Anstie. "There have been good studies undertaken around the world which show that diseases like lung and esophageal cancer, asthma and diabetes can be detected in this way, even before external symptoms are showing." The spectrometer technology offers a possible path to noninvasive, real-time health screening. It has already been validated by comparison with a previous high-precision absorption measurement of hydrogen cyanide near 1543 nm. "We now have a robust system to be able to detect the presence and concentrations of molecules in a sample," Anstie said. "The next step is to work out how to accurately sample and interpret the levels, which will naturally vary from person to person." The researchers hope to have a working prototype in two to three years and a commercial "plug-and-play" product in three to five years. Other potential applications include measuring trace gasses, such as atmospheric carbon dioxide, and detecting impurities in natural-gas streams. Funding came from the Australian Research Council, the Premier's Research and Industry Fund and a South Australian Government Catalyst Research Grant. The research was published in Optics Express (doi: 10.1364/OE.23.013991 [open access]). For more information, visit www.adelaide.edu.au.